Self-lubricated rotary joint

ABSTRACT

An assembly for electrically coupling a first coaxial cable to a second coaxial cable for rotation relative to one another is disclosed and generally comprises a pair of sub-assemblies which electrically connect the inner and outer conductors of the first cable to respective inner and outer conductors of the second cable while substantially eliminating frictional wear therebetween.

Munson et al.

lQS a l [19] 1 Jan. 15, 1974 SELF-LUBRICATED ROTARY JOINT [75] Inventors: Robert E. Munson; Jerry H. Polson; Kent G. Roller, all of Boulder, C010.

[73] Assignee: Ball Brothers Research Corporation,

Boulder, C010.

[22] Filed: Dec. 18, 1970 [21] Appl. No.: 99,483

[52] US. Cl 333/97 R, 333/24 C, 333/98 TN,

339/5 P, 339/8 PB [51] lnt. Cl. lllOlp l/06 [58] Field of Search 333/24 C, 33, 35,

[56] References Cited UNITED STATES PATENTS 2,700,137 1/1955 Ragan .[333/97 2,918,638 12/1959 Cattoi et a1. 333 97 2,602,118 7/1952 Adams et a1. 333/24 C 2,434,475 l/l948 Sullivan 339/115 R X 2,181,145 11/1939 Mose 339/8 PB 1,070,307 8/1913 Twining... 339/8 P 1,665,018 4/1928 Black 339/8 P UX 2,541,836 2/1951 Salisbury l 333/97 1,199,172 9/1916 Garrison 339/8 P 2,210,827 8/1940 Zaborsky 339/115 R Primary ExaminerPaul L. Gensler Att0rneyGilbert E. Alberding 5 7 ABSTRACT An assembly for electrically coupling a first coaxial cable to a second coaxial cable for rotation relative to one another is disclosed and generally comprises a pair of sub-assemblies which electrically connect the inner and outer conductors of the first cable to respective inner and outer conductors of the second cable while substantially eliminating frictional wear therebetween.

6 Claims, 6 Drawing Figures PATENTEDJAW 15 I974 SHEET 1 F 3 4bl3 2o 26 57 A 5 igo 1 38 28 7 /W 2/ I 27 i, a I? 26 .1 0 46 W I 22%;? 49 32 4O LUBRICATION RESERVOIR BY 0M ATTOR NEY PATENTEDJM 15 I974 Figo 4 INVENTOR ROBERT E. MUNSON JERRY H. POLSON KENT G. ROLLER BY 4% a 0M SHEET 2 0F 2 ATTORNEY SELF-LUBRICATIED ROTARY JOINT BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to connecting assemblies and more particularly to an improved rotary joint assembly.

2. Description of the Prior Art Presently, there are many diverse and highly technological operations, such as, for example, those required in the exploration of outer space, which require rather complex long range or, for that matter, short range communication systems. For example, rockets are being utilized for carrying highly complex instrument payloads into space where valuable data is collected and transmitted back to receiving stations here on earth.

I-Ieretofore, there have been many problems encountered in providing the necessary communication systems, one of which has been the loss in transmission and reception of signal energy, due, in part, to malfunctions in rotating components of the antenna system provided therewith. One reason for these malfunctions has been the inability to provide a reliable rotary joint which would otherwise allow the antenna system components to continuously rotate over long periods of time without fear of inoperation through frictional wear, While the prior art discloses various types of friction minimizing rotary type joints, there has not been heretofore, a joint which has completely solved the problem by being both reliable in operation and, at the same time, capable of efficiently coupling energy signals especially of the microwave frequency range, necessary for the above exemplified operation as well as other types thereof.

SUMMARY OF THE INVENTION The present invention overcomes the aforementioned deficiencies, as well as other deficiencies, by providinga self-lubricated rotary joint assembly which is constructed so as to substantially eliminate frictional wear between the various components thereof and yet which is capable of efficiently coupling together a pair of microwave signal carrying coaxial cables at a low VSWR and low insertion loss.

As will be seen hereinafter, a preferred embodiment of the rotary joint assembly constructed in accordance with the present invention is provided for electrically joining a first pair of conductors to a second pair of conductors and for rotating one pair relative to the other. The assembly generally comprises first means adapted for electrically connecting a first conductor of said first pair with a first conductor of said second pair and includes a pair of physically spaced apart but effectively electrically connected coupling elements, each of which is adapted for engagement with a respective one of said first conductors. The assembly further includes second means for electrically connecting a second conductor of said first pair to a second conductor of said second pair and means for electrically insulating said first means from said second means.

Accordingly, a general object of the present invention is to provide a newand improved rotary joint assembly which operates with greater reliability than those of the prior art.

Another object of the present invention is to provide a new and improved self-lubricated rotary joint assembly which substantially eliminates frictional wear be tween components thereof.

Yet another object of the present invention is to provide a rotary joint assembly of the aforestated type which minimizes the area of physical engagement between components thereof.

Still another object of the present invention is to provide a rotary joint assembly of the aforestated type which continuously and automatically distributes lubrication to its components.

A further object of the present invention is to provide a new and improved self-lubricated rotary joint which more reliably electrically connects a pair of conductors together.

Yet a further object of the present invention is to pro vide a new and improvedself-lubricated rotary joint assembly which more efficiently transfers electrical signals and particularly microwave electrical signals from one coaxial cable to another.

Still a further object of the present invention is to provide a rotary joint assembly which is small in size and low in insertion loss and which allows for a broad bandwidth of signals at a low VSWR.

These and other objects and advantages will become more apparent to those skilled in the art from the following descriptions.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a self-lubricated rotary joint assembly constructed in accordance with a preferred embodiment of the present invention;

FIG. 2 is a perspective view of the rotary joint assembly of FIG. 1, specifically showing the components thereof in an opened or disconnected manner;

FIG. 3 is a sectional view taken generally on line 33 in FIG. 1;

FIG. 4 is a schematic view of an electrical circuit which is electrically equivalent to the rotary joint assembly of FIG. 1;

FIG. 5 is a cross-sectional view of a self-lubricated rotary joint assembly constructed in accordance with a second embodiment of the present invention; and

FIG. 6 is a sectional view taken generally along line 6-6 in FIG. 5.

DETAILED DESCRIPTION Turning now to the drawings, wherein like components are designated by like reference numerals throughout the various figures, a self-lubricated rotary joint assembly 10, constructed in acordance with a preferred embodiment of the present invention, is shown in FIGS. ll, 2 and 3 connected between and to a first coaxial cable 12 and a second coaxial cable 14. Assembly 10, as will be discussed in more detail hereinafter, is provided for electrically connecting coaxial cable 12 to coaxial cable 14 while, at the same time having the capability of rotating one cable relative to the other or of rotating both simultaneously and in opposite directions. An antenna device (not shown) may be connected to the otherwise free end of one of the coaxial cables and a transmitter and/or receiver device (not shown) may be connected to the otherwise free end of the other coaxial cable. In this manner, the antenna device may be rotated (spun) relative to its transmitter and/or receiver device or the receiver and/or transmitter device may be rotated (spun) relative to the antenna device, these, of course, being only a few of the ways in which rotary joint assembly may be used.

As illustrated best in FIG. 3, rotary joint assembly 10 includes a first or outer sub-assembly 16 for capacitively connecting the outer conductor 18 of coaxial cable 12 to the outer conductor 20 of coaxial cable 14 and a concentrically positioned inner sub-assembly 22 for physically connecting the inner conductor 24 of coaxial cable 12 to the inner conductor 26 of coaxial cable 14. As will be described in more detail hereinafter, a rotation imparting drive assembly 27 (FIG. 1) is coupled to sub-assemblies l6 and 22 for axially rotating one or both of the coaxial cables relative to each other.

Outer sub-assembly 16 is comprised of a pair of physically spaced apart and electrically conductive capacitive elements 28, each of which includes a ring-shaped disc portion 30 defining an axially positioned circular opening 32. Each of the capacitive elements further includes an open ended cylindrical housing or connector means 34 which is preferably integrally formed with but which, in any case, is mounted centrally to one side of a respective disc portion 30 and circumscribes circular opening 32. In this manner, the disc portions and cylindrical housing cooperate with each other to define a pair of axially spaced apart cylindrical cavities 36 which, as will be seen hereinafter, concentrically receive inner sub-assembly 22.

As illustrated best in FIG. 1, the outer conductor 18 of coaxial cable 12 and the outer conductor 20 of coaxial cable 14 are soldered or otherwise suitably electrically and mechanically connected to the axially facing backsides 38 of cylindrical housing 34 while inner conductors 24 and 26 extend into corresponding cavities 36 through cooperating apertures in backsides 38, as illustrated best in FIG. 3.

Outer sub-assembly 16, constructed in the aforedescribed manner, defines a pair of physically spaced apart confronting surfaces 40, best illustrated in FIG. 3. As will be seen hereinafter, these confronting surfaces are spaced apart a predetermined distance and are appropriately dimensioned so as to provide therebetween capacitive impedance which is negligible compared to the overall impedance of coaxial cables 12 and 14. In this manner, sub-assembly 16 provides an effective electrical circuit between the outer conductors l8 and 20 of the coaxial cables.

Turning now specifically to FIG. 2 and 3, attention is directed to inner sub-assembly 22, which, as stated above, is provided for electrically connecting the inner conductor of coaxial cable 12 to the inner conductor of coaxial cable 14. As seen in these figures, subassembly 22 includes an electrically conductive cylindrical cap 42 which is positioned axially within one of the coaxial cavities 36 and which is mounted over and to a cavity inserted end of inner conductor 24. In this regard, dielectric material 43 may be provided within cavity 36 for supporting cap 42 as well as for insulating the same from capacitive element 28. A partially resilient conductive ring element 44 is soldered or otherwise suitably electrically and mechanically mounted to the free end of cap 42 and extends axially outwardly therefrom. While this ring element may be constructed of any suitable resilient conductive material it is preferably made of a beryllium-copper alloy coated with hard gold.

Sub-assembly 22 further includes a second electrically conductive cylindrical cap 46 which is axially positioned within the otherwise free coaxial cavity 36 and which is mounted to the cavity inserted end of inner conductor 26, the cap being supported within the cavity by insulation material 47 in the same manner as cap 42. The two caps 42 and 46 are axially positioned relative to each other so that a circumferential portion of ring element 44 rotatably and resiliently engages the base or otherwise free end portion 49 of cap 46, which free end portion 49 preferably includes a coating of silver-gold alloy. In this manner, sub-assembly 22 directly electrically connects the inner conductor of coaxial cable 12 to the inner conductor of coaxial cable 14. It should be noted that the caps, cavities and insulating material are suitably dimensioned to maintain the effective impedance of the coaxial cables as they enter the cavities.

As illustrated in FIG. 2 and 3, sub-assembly 22 also includes a conventional lubrication reservoir 48 comprising, for example, sponge material, preferably nylon, which is suitably mounted on a shoulder 50 provided integrally with and circumscribing cap 46 so that the reservoir is exposed to the point of engagement of ring 44 and 46. An evaporating type lubricant such as, for example, low vapor pressure paraffinic hydrocarbon containing a metallo-organic pressure additive is impregnated in sponge reservoir 48 (and also may initially be placed on the ring and cap contact point). In this manner, the lubricant continuously evaporates and in so doing developes a fine mist which condensates at various points throughout the rotary joint assembly and particularly at the aforestated contact point for providing continuous lubrication at these points. This, of course, is quite advantageous when the rotary joint assembly is used for example, in long term outer-space operations. By providing this continuous lubrication, frictional wear between the various components of rotary joint assembly 10 is substantially eliminated.

Returning to FIG. 1 self-lubricated rotary joint assembly 10 is shown to include rotation imparting drive assembly 27 which, as stated above, is provided for axially rotating coaxial cable 12 or coaxial cable 14. This assembly is conventional and may include, for example, a drive motor 51 mounted to a gear arrangement 53 through a drive shaft 55, the gear arrangement being adapted for engagement with one of the capacitive elements 28 as illustrated in FIG. 1. In this manner motor 51 drives element 28 through the gear arrangement which, in turn, axially rotates coaxial cable 14. It should be apparent that drive assembly 27 and particularly gear arrangement 53 can easily be modified to drive the other capacitive element and therefore axially rotate coaxial cable 12 or drive both of the capacitive elements simultaneously and in opposite directions.

Because rotation imparting drive assembly 27 is conventional and does not per se form a part of the invention, it is only shown in FIG. 1 and, for purposes of clarity, is completely eliminated in FIGS. 2 and 3. It is to be understood that any suitable means for achieving the results attributed to drive assembly 27 is contemplated by the invention.

The entire rotary joint assembly 10 may be supported in any conventional manner. For example, as illustrated in FIG. 1, a pair of fixed bearing flanges 57 held to a support structure (not shown) may be mounted around coaxial cables 12 and 14 for supporting assembly 10 while, at the same time, allowing the assembly and coaxial cables to rotate in the manner described hereinabove.

With self-lubricated rotary joint assembly constructed in the aforedescribed manner, attention is now directed to its operation. For purposes of example, let it be assumed that coaxial cables 12 and 14 are provided for transferring electrical signal energy in the microwave frequency range between an antenna device (not shown) and a receiver and/or transmitter device (shown). Let it further be assumed that the combined impedance of coaxial cables 12 and 14 connecting the two is approximately equal to 50 ohms, which is gener ally the case when operating at such a high frequency.

By connecting rotary joint assembly 10 to the adjacent free ends of the coaxial cables, in the aforedescribed manner, it is readily apparent that inner subassembly 22 provides a short circuit between the inner conductors therof, which short circuit is effectively in series with the combined impedance of the coaxial cables. This may be best illustrated by a circuit 54 which is shown in FIG. 4 and which is electrically equivalent to the connected combination of the rotary joint assembly and coaxial cables 12 and 14. As seen in this figure, a 50 ohm resistorwhich is generally designated by the reference numeral 56 and which represents the overall impedance of coaxial cable 12 and 14 is electrically connected in series with a short circuit which is generally designated by the reference numeral 58 and which represents the short circuit provided by sub-assembly 22.

As stated above, the outer conductors 18 and 20 of respective coaxial cables 12 and 14 are capacitively connected together by outer sub-assembly 16 which includes confronting surfaces 40. In this manner, capacitive impedance, which will be generally referred to as X developes between these two confronting surfaces and in electrical series with the overall impedance of coaxial cables 12 and 14 as indicated by the series connected capacitor 60 in FIG. 4. As will be seen, the value of impedance X is appropriately chosen so as to be of negligible concern compared to the overall coaxial cable impedance and therefore provides an effective short circuit between outer conductors 18 and 20.

The value of impedance X is determined by resorting to the standard equation for capacitive impedance which is:

Where X is the capacitive reactance of ohms, F is the frequency in cycles and C, the capacitance farads. The capacitance, in turn, is given by the standard equation:

Where C is the capacitance in farads, s is the constant for conductivity of free space, A is the surface area of each of the confronting surfaces 40, and g is the gap between these confronting surfaces. It may readily be appreciated that by appropriately choosing the values of surface areas A and gap g along with a particular operating frequency, a desirable value for capacitive reactance X may be provided. In this regard, it has been found that when operating at a frequency in the microwave range and when utilizing coaxial cables having a combined impedance of approximately ohms, the most effective value for capacitive reactance X is approximately ,-2 ohms or less. For example. with assembly 10 operating to transfer signals having a frequency of approximately 2,000 MI-lz, the values of surface areas A and gap g could be approximately 1.62 square inches and (1/100) inch, respectively, so as to provide a capacitive reactance X equal to approximately 2 ohms.

Upon comparing the ,2 ohm value of capacitive reac tance X with that of the 50 ohm resistor 56 representing the overall cable impedance in FIG. 4, it is readily apparent that the former is of negligible value compared to the latter and thereby provides an effective electrical short circuit between the outer conductors 18 and 20 of the coaxial cables. In addition, it has been found that this particular value of capacitive reactance provides a VSWR of approximately 120421 so as to substantially match the impedance of the outer conductors and further provides for a broad bandwidth and extremely low insertion loss.

While the aforementioned example was directed to the transmission of microwave frequency signals utilizing coaxial cables displaying approximately 50 ohms overall impedance and capacitive coupling elements displaying approximately ,-2 ohms capacitive impedance, it is to be understood that the invention contemplated herein is not limited thereto and, for example, may be utilized for transferring signals of lesser frequencies and under conditions of different impedance values, that is, the invention is not limited to the utilization of 50 ohm coaxial cables or capacitive impedance of -2 ohms so long as the capacitive impedance is negligible compared to the impedance of the coaxial cables.

Turning now to FIGS. 5 and 6, a self-lubricated rotary joint assembly 60, constructed in accordance with an alternate embodiment of the present invention, is shown connected between and to a first coaxial cable 62 and a second coaxial cable 64. Like self-lubricated rotary joint assembly 10, assembly 60 is provided for electrically connecting coaxial cable 62 to coaxial cable 64 while, at the same time, having the capability to rotate one cable relative to the other or both simultaneously. However, as will be seen hereinafter, assembly 60 utilizes a quarter-wave short circuit technique for electrically coupling the outer conductors of the coaxial cables as opposed to the capacitive coupling technique utilized by and described with respect to assembly 10. In this manner, the attained VSWR is substantially equal to one, thereby completely matching the impedance between the two outer conductors.

As illustrated best in FIG. 5, rotary joint assembly 60 includes a first or outer sub-assembly 66 for electrically connecting the outer conductor 68 of coaxial cable 62 to the outer conductor 70 of coaxial cable 64 by a quarter-wave short circuit technique to be described below. A concentrically positioned inner sub-assembly 72 is provided for electrically connecting the inner conductor 74 of coaxial cable 62 to the inner conductor 76 of coaxial cable 64 in substantially the same manner as described with respect to rotary joint assembly 10.

Outer sub-assembly 66 includes a first array of electrical conductors 78 and a second array of conductors 80 which are respectively connected to the outer conductors 68 and 70 of coaxial cables 62 and 64 and which are spaced apart from each other so as to define an open circuit therebetween. As will be seen hereinafter, arrays 78 and 80 are appropriately dimensioned and appropriately positioned relative to each other so as to transform the aforestated open circuit into an effective electrical short circuit upon receipt of an alternating electrical signal of the frequency for which the assembly has been constructed and thereby electrically connect outer conductor 68 to outer conductor 70.

Array 80 includes a pair of concentrically positioned and radially spaced cylindrical conductors 82 and 84 and a cylindrical electrically conductive extension 86 which is smaller in cross-section than conductors 82 and 84 and which is integrally connected with common transverse edges of the concentric conductors by a ring-shaped shoulder 88 extending radially outwardly from one end of the extension, as illustrated in FIG. 5. In this manner, an electrical short circuit, generally indicated by the reference numeral 90 is provided between conductors 82 and 84. For reasons to be described hereinafter, the axial length of each of these conductors is approximately one-quarter wavelength at the anticipated signal frequency carried through the rotary joint assembly.

Outer conductor 70 of coaxial cable 64 is soldered or otherwise suitably electrically connected to array 80 at a radially outwardly extending flange 91 integrally provided with the otherwise free end of extension 86, as illustrated in FIG. 5.

Array 78 comprises a cylindrical conductor 92 having an integrally formed flange 94 which extends radially outwardly and which is soldered or otherwise suitably electrically connected to the outer conductor 68 of coaxial cable 62. As illustrated in FIG. 5, conductor 92, which displays a cross-sectional diameter slightly less than that of cylindrical conductor 84, extends inwardly into the latter a distance slightly less than onequarter wavelength at the aforementioned signal carrying frequency and is axially spaced from ring-shaped shoulder 88 so as to define an electrical open circuit 94 therebetween. Array 78 further includes a radially outwardly extending ring-shaped conductive shoulder 96 which is preferably integrally formed with and which circumscribes conductor 92 at a point approximately one-quarter wavelength from the otherwise free end of conductor 92. Shoulder 96 extends outwardly a sufficient distance so as to confront both of the otherwise free transverse edges of concentric conductors 82 and 84 and is axially spaced therefrom so as to define an electrical open circuit 96 therebetween.

It is readily apparent that conductor arrays 78 and 80, constructed and positioned in the aforedescribed manner, define a first one-quarter wavelength coaxial cavity 100 having a short circuited end 90 and an open circuited end 98 and a second one-quarter wavelength coaxial cavity 102 having an open circuited end 94 and an open circuited end 98. Further, from a knowledge of conventional quarter-wave short circuit techniques, it is equally readily apparent that upon receipt of the aforestated alternating electrical signal, short circuit 90 transforms, impedencewise, to an open circuit a quarter-wavelength therefrom or at open circuit 98. Thereafter, the open circuit 98 transforms, impedance-wise, to a short circuit one-quarter wavelength therefrom or at open circuit 94. Accordingly, from an impedance standpoint, open circuit 94 is effectively a short circuit which, in turn, electrically connects cylindrical conductor 92 to cylindrical conductive extension 86. Therefore, outer subassembly 66 electrically connects the outer conductor 68 of coaxial cable 62to the outer conductor of coaxial cable 64 while maintaining the VSWR substantially at unity.

Attention is now directed to inner sub-assembly 72, which as stated above, is provided for electrically connecting the inner conductor of coaxial cable 62 to the inner conductor of coaxial cable 64. As seen best in FIG. 5, sub-assembly 72 includes an electrically conductive cylindrical cap or extension 104 which is positioned axially within conductor 92 of outer subassembly 66 and which includes at one end thereof an integrally radially extending flange portion 106 soldered or otherwise suitably electrically and mechanically connected with inner conductor 74 of coaxial cable 62. A partially resilient conductive ring-shaped element 108 preferably constructed of the same material as ring 44, is soldered or otherwise suitably mounted to the otherwise free end of cap extension 104 and extends axially outwardly therefrom.

Sub-assembly 72 further includes a second electrically conductive cylindrical cap or extension 110 which includes a lubrication reservoir 112 identical in structure and function to that of reservoir 48 and which is circumferentially positioned about and to a shoulder 113 integrally formed with extension 110, as illustrated in FIG. 5. Like extension 104, extension 110 includes an integral radially extending flange portion 114 which is soldered or otherwise suitably electrically and mechanically connected with inner conductor 76 of coaxial cable 64. The two extensions 104 and 110 are positioned in axial alignment and are axially spaced from each other so that a circumferential portion of ring element 108 rotatably and resiliently engages the base or otherwise free end portion 1 16 of extension 110, which end portion is preferably coated with the same material as surface 49 described hereinabove. In this manner, sub-assembly 72 electrically connects the inner conductor of coaxial cable 62 to the inner conductor of coaxial cable 64.

While not shown in FIG. 5, rotary joint assembly 60 includes a conventional rotation imparting drive assembly, such as assembly 27 shown in FIG. 1, which may be adapted for rotating coaxial cable 62, coaxial cable 64, or both, simultaneously and in opposite directions as described hereinabove. In this regard, a pair of dielectric washers 122 are positioned concentrically between and connected to the inner and outer sub assembly so that upon rotating the outer sub-assembly the inner sub-assembly will rotate therewith. In addition, the entire assembly may be supported in the same manner as assembly 10, such as, for example, by the utilization of flanges 57.

Although various embodiments of the present invention have been illustrated and described, it is anticipated that various changes and modifications will be apparent to those skilled in the art and that such changes may be made without departing from the scope of the invention as defined by the following claims.

What is claimed is:

1. An assembly for electrically joining a first pair of conductors to a second pair of conductors and for rotating one pair relative to the other, said assembly comprising: first means for electrically connecting a first conductor of said first pair with a first conductor of said second pair, said first means including a pair of physically spaced-apart but effectively electrically connected coupling elements, each of which is engageable with a respective one of said first conductors; second means for electrically connecting a second conductor of said first pair with a second conductor ofsaid second pair, said second means including rotatable joint means having a base element mountable to one of said second conductors and a partially resilient ring element having one circumferential portion mountable to the other of said second conductors and a second circumferential portion spaced from said first portion and rotatably engagable against said base element; and insulation means for electrically insulating said first means from said second means.

2. An assembly for electrically joining a first pair of conductors to a second pair of conductors and for rotating one pair relative to the other, said assembly comprising: first means for electrically connecting a first conductor of said first pair with a first conductor of said second pair, said first means including a pair of physically spaced-apart but effectively electrically connected coupling elements, each of which is engageable with a respective one of said first conductors; second means for electrically connecting a second conductor of said first pair with a second conductor of said second pair; said second means including rotatable joint means having a base element mountable to one of said second conductors and a partially resilient ring element having one circumferential portion mountable to the other of said second conductors and a second circumferential portion spaced from said first portion and rotatably engageable against said base element, said second means also including means for continuously minimizing friction at said joint means, said friction minimizing means including a lubrication reservoir adapted for substantially continuously providing lubrication to said joint means.

3. An assembly for electrically joining a first pair of conductors to a second pair of conductors and for rotating one pair relative to the other, said assembly comprising: first means for electrically connecting a first conductor of said first pair with a first conductor of said second pair, said first means including a pair of physically spaced-apart but effectively electrically connected coupling elements, said coupling elements including physically spaced-apart centrally apertured discs having substantially flat confronting surfaces which cooperate to provide capacitive coupling of said elements upon receipt of an alternating electrical signal, said first means also including first and second connector means each of which has a substantially cylindrical portion connected to and surrounding said centrally apertured portion of a different one of said discs, each of said connector means being connected with a different one of said first conductors; second means for electrically connecting a second conductor of said first pair with a second conductor of said second pair; and insulation means for electrically insulating said first means from said second means.

4. An assembly for joining one electrical conductor to a second electrical conductor, said assembly comprising: rotatable joint means engageable with said conductors and adapted for allowing at least one of said conductors to axially rotate relative to the other conductor; said joint means being constructed of electrically conductive material for electrically connecting said conductors together and having a base element mountable to one of said second conductors and a partially resilient ring element having one circumferential portion mountable to the other of said second conductors and a second circumferential portion spaced from said first portion and rotatable engageable against said base element; and a lubrication reservoir positioned adjacent said joint means and adapted for substantially continuously providing lubrication to said joint means whereby minimizing frictional wear thereat.

5. An assembly for joining one electrical conductor to a second electrical conductor, said assembly comprising: an electrically conductive base element mountable to one of said conductors; a partially resilient electrically conductive ring element having one circumferential portion mountable to the other of said conductors and a second circumferential portion spaced from said first portion and rotatable engagable with said base element; and means for supporting said contact ele ment and said base element.

6. An assembly for electrically joining a pair of conductors and for rotating the same relative to each other, said assembly comprising: a first coupling element including a first centrally apertured disc having a first surface having a predetermined substantially flat surface area, said first coupling element also including a first cylindrical connector connected at one end to said first disc so as to surround the central aperture therein, the other end of said connector being connected with one of said conductors; a second coupling element including a second centrally apertured disc having a second surface having a predetermined substantially flat surface area, said second coupling element also including a second cylindrical connector connected at one end to said second disc so as to surround the central aperture therein, the other end of said connector being connected with the other of said conductors; means for supporting said second surface a predetermined distance from and in confronting relationship with said first surface, the values of said predetermined surface areas and said predetermined distance being such that an effective short circuit is provided between said coupling elements upon receipt of an alternating electrical signal; and means for rotating at least one of said coupling elements relative to the other coupling element. 

1. An assembly for electrically joining a first pair of conductors to a second pair of conductors and for rotating one pair relative to the other, said assembly comprising: first means for electrically connecting a first conductor of said first pair with a first conductor of said second pair, said first means including a pair of physically spaced-apart but effectively electrically connected coupling elements, each of which is engageable with a respective one of said first conductors; second means for electrically connecting a second conductor of said first pair with a second conductor of said second pair, said second means including rotatable joint means having a base element mountable to one of said second conductors and a partially resilient ring element having one circumferential portion mountable to the other of said second conductors and a second circumferential portion spaced from said first portion and rotatably engagable against said base element; and insulation means for electrically insulating said first means from said second means.
 2. An assembly for electrically joining a first pair of conductors to a second pair of conductors and for rotating one pair relative to the other, said assembly comprising: first means for electrically connecting a first conductor of said first pair with a first conductor of said second pair, said first means including a pair of physically spaced-apart but effectively electrically connected coupling elements, each of which is engageable with a respective one of said first conductors; second means for electrically connecting a second conductor of said first pair with a second conductor of said second pair; said second means including rotatable joint means having a base element mountable to one of said second conductors and a partially resilient ring element having one circumferential portion mountable to the other of said second conductors and a second circumferential portion spaced from said first portion and rotatably engageable against said base element, said second means also including means for continuously minimizing friction at said joint means, said friction minimizing means including a lubrication reservoir adapted for substantially continuously providing lubrication to said joint means.
 3. An assembly for electrically joining a first pair of conductors to a second pair of conductors and for rotating one pair relative to the other, said assembly comprising: first means for electrically connecting a first conductor of said first pair with a first conductor of said second pair, said first means including a pair of physically spaced-apart but effectively electrically connected coupling elements, said coupling elements including physically spaced-apart centrally apertured discs having substantially flat confronting surfaces which cooperate to provide capacitive coupling of said elements upon receipt of an alternating electrical signal, said first means also including first and second connector means each of which has a substantially cylindrical portion connected to and surrounding said centrally apertured portion of a different one of said discs, each of said connector means being connected with a different one of said first conductors; second means for electrically connecting a second conductor of said first pair with a second conductor of said second pair; and insulation means for electrically insulating said first means from said second means.
 4. An assembly for joining one electrical conductor to a second electrical conductor, said assembly comprising: rotatable joint means engageable with said conductors and adapted for allowing at least one of said conductors to axially rotate relative to the other conductor; said joint means being constructed of electrically conductive material for electrically connecting said conductors together and having a base element mouNtable to one of said second conductors and a partially resilient ring element having one circumferential portion mountable to the other of said second conductors and a second circumferential portion spaced from said first portion and rotatable engageable against said base element; and a lubrication reservoir positioned adjacent said joint means and adapted for substantially continuously providing lubrication to said joint means whereby minimizing frictional wear thereat.
 5. An assembly for joining one electrical conductor to a second electrical conductor, said assembly comprising: an electrically conductive base element mountable to one of said conductors; a partially resilient electrically conductive ring element having one circumferential portion mountable to the other of said conductors and a second circumferential portion spaced from said first portion and rotatable engagable with said base element; and means for supporting said contact element and said base element.
 6. An assembly for electrically joining a pair of conductors and for rotating the same relative to each other, said assembly comprising: a first coupling element including a first centrally apertured disc having a first surface having a predetermined substantially flat surface area, said first coupling element also including a first cylindrical connector connected at one end to said first disc so as to surround the central aperture therein, the other end of said connector being connected with one of said conductors; a second coupling element including a second centrally apertured disc having a second surface having a predetermined substantially flat surface area, said second coupling element also including a second cylindrical connector connected at one end to said second disc so as to surround the central aperture therein, the other end of said connector being connected with the other of said conductors; means for supporting said second surface a predetermined distance from and in confronting relationship with said first surface, the values of said predetermined surface areas and said predetermined distance being such that an effective short circuit is provided between said coupling elements upon receipt of an alternating electrical signal; and means for rotating at least one of said coupling elements relative to the other coupling element. 